1. Field of the Invention
This invention relates to a pump piston and, more particularly, to a pump piston that has a sealing means independent of the pressure applied by the hub thereto when operating within a pump cylinder.
2. Description of the Prior Art
At the present time, there is a great variety of pump pistons, generally each being designed for a particular pump. As is well known in the art, various problems and difficulties are encountered in providing a piston that is positive in its sealing arrangement, whereby after a short period of time the pumping material seeps past the piston and causes damage to the piston cylinder and rod as well as to the sealing means therein.
Also, there is lacking a piston that can be operated for long periods of time when exposed to high pressures and abrasive materials that might be pumped therethrough, such as oil well sump mud.
Other problems encountered with many pistons are in their repair and replacement.
Some of the well known and often used pistons are illustrated in various U.S. patents. As an example, U.S. Pat. No. 2,349,784 shows a single piston head slidably disposed within a cylinder.
Patents which go back to the year of 1895, such as U.S. Pat. No. 541,682, illustrate the typical piston having the well known packings with annular-extending lips as indicated.
Again, a very similar piston is shown in U.S. Pat. No. 1,335,051 which in this case is applied to an air pump.
U.S. Pat. Nos. 528,378, 391,435 and 764,900 all provide two reverse cup-shaped packings clamped between respective support discs.
Hence, there is a need for a pump piston capable of being used in various devices under many different conditions.